This invention relates to audible and audible/visual warning devices. For the sake of safety and efficiency, it is important that operators of machinery and other equipment experience sensory feedback when operating machine and equipment controls. Sensory feedback may be audible, visual or tactile, and it is common to provide only one kind of sensory feedback, such as an audible warning device emitting only sound.
More recently, to keep pace with machine designers who continually strive to reduce size and cut costs in order to provide greater value to their customers, sensory devices have been developed which offer more than one kind of sensory feedback in a single package. For example, audible devices are available which have an embedded light-emitting diode (LED) so that both audible and visual signals can be generated simultaneously. It is also known to incorporate a light in a pushbutton switch, e.g., to provide a visual indication to help the operator more quickly locate the switch.
However, sensory device designers have faced challenges in providing multi-sensory warning devices in compact packages and achieving desired levels of performance and cost. For example, in panel-mount alarms employing a sound generating element such as a speaker or piezoelectric transducer, the housing is generally sized for the speaker or transducer so there is little or no side space available for a light source. Rear lighting presents problems because conventional speakers and piezoelectric transducers are opaque, and front mounting of a light source presents problems due to the need for electrical wiring for the light source. One approach to front mounting involves running wires through holes created in a piezoelectric transducer, as described in U.S. Pat. No. 6,130,618, which is incorporated herein by reference. As an alternative, it has been proposed to provide lighting from inside the panel in which the warning device is mounted, using LEDs mounted behind the piezoelectric transducer in a light-transmissive housing so that light is transmitted around the transducer from behind the plane of the panel through a length of the housing wall, as described in U.S. Pat. No. 7,920,069. Such a design compromises the brightness of the light emitted from the warning device.
A need remains for improvements in the design of warning devices in compact packages, particularly warning devices which integrate sound and light and/or other functions in housings suitable for panel mounting or similar applications.